The present invention relates to a method and apparatus for initializing vehicle-mounted computers, and particularly to the method and apparatus for initializing the vehicle-mounted computers each time when supplying the electric power of a battery is started and when cranking an engine is terminated.
It has been known in the field of controls for an automotive vehicle that operations of the vehicle are controlled electronically by a digital computer programmed to perform various calculating operations in accordance with a preestablished operating sequence. Some of these controls are disclosed in U.S. Pat. No. 3,835,819 of Anderson and 3,969,614 of Moyer et al in which controls for the vehicle are directed to the controls for the fuel supply, ignition and so forth of internal combustion engines mounted on the vehicle. In these patents, the digital computer is programmed to perform various calculating operations on a time-sharing and software basis in accordance with the operating sequence preestablished therein.
It has been also known that the digital computer must be initialized prior to starting the required calculating operations. With regard to initializing the computer, no suggestion has been made in the above-identified patents.
From the standpoint that the computer is generally intialized at the start of operating the computer, a first attempt was made in which the computer mounted on the vehicle for controlling the fuel supply and ignition of the engine was intialized at the start of connecting the storage battery of the vehicle to the computer through a constant voltage circuit. It was observed very often in many experiments conducted on this arrangement that the computer stopped the calculating operations at the end of cranking the engine and the engine was caused to stall thereafter. This drawback was analysed to result from a negative electric noise signal which appeared on a power supply bus at the end of cranking the engine. Since the electric power from the battery is supplied to the computer through the power supply bus and the constant voltage circuit, the constant voltage produced by the constant voltage circuit to maintain the operative condition of the computer is not produced while the negative noise signal appears. This results in the stoppage of the calculating operations of the computer.